爆肝Week05

Week05：移動、旋轉、縮放、矩陣

範例 http://jsyeh.org/3dcg10

1. 下載網頁中的data, win32

2. 將windows解壓縮, data.zip/data丟進解壓縮後的windows資料夾

 3.開啟Translate.exe
    按Alt+S可以交換位移(glTranslatef)與旋轉(glRotatef)
    順序不同，效果也不同

鍵盤事件glutKeyboardFunc()

1.使用先前的茶壺程式碼，加上keyboard函式並利用printf()印出執行的動作
```

#include <stdio.h>///印出用

#include <GL/glut.h>

void display()

{

    glClear(GL_COLOR_BUFFER_BIT |GL_DEPTH_BUFFER_BIT);

    glColor3f(1, 1, 0);

    glutSolidTeapot(0.3);

    glutSwapBuffers();

}

void keyboard( unsigned char key, int x, int y )

{

    printf("你按下了%c在 %d %d座標\n", key, x, y);

}

int main(int argc, char** argv)

{

    glutInit( &argc, argv);

    glutInitDisplayMode( GLUT_DOUBLE | GLUT_DEPTH );

    glutCreateWindow("week05 keyboard");

    glutDisplayFunc(display);

    glutKeyboardFunc(keyboard);///鍵盤事件函式

    glutMainLoop();

}

```

2-1.加上先前教過的Motion與Mouse函式
```

#include <stdio.h>///印出用

#include <GL/glut.h>

float x=0, y=0, z=0;

int oldX=0, oldY=0;

void display()

{

    glClear(GL_COLOR_BUFFER_BIT |GL_DEPTH_BUFFER_BIT);

    glPushMatrix();

        glTranslatef((x-150)/150.0, -(y-150)/150.0, z);

        glColor3f(1, 1, 0);

        glutSolidTeapot(0.3);

    glPopMatrix();

    glutSwapBuffers();

}

void mouse(int button, int state, int mouseX, int mouseY)

{

}

void motion(int mouseX, int mouseY)

{

}

void keyboard( unsigned char key, int mouseX, int mouseY )

{

}

int main(int argc, char** argv)

{

    glutInit( &argc, argv);

    glutInitDisplayMode( GLUT_DOUBLE | GLUT_DEPTH );

    glutCreateWindow("week05 keyboard");

    glutDisplayFunc(display);

    glutKeyboardFunc(keyboard);///鍵盤事件函式

    glutMouseFunc(mouse);

    glutMotionFunc(motion);

    glutMainLoop();

}

```

2-2.在Motion拖曳函式中加上參式與重設座標的公式

```

void motion(int mouseX, int mouseY)

{

    x +=(mouseX-oldX);

    y +=(mouseY-oldY);

    oldX = mouseX;

    oldY = mouseY;

    display();

}

```

2-3.在 mouse函式中設置錨點，去除圖形瞬移的錯誤

```

#include <stdio.h>///印出用

#include <GL/glut.h>

float x=150, y=150, z=0;///座標設定為150, 150在視窗正中央

int oldX=0, oldY=0;

void display()

{

    glClearColor(0.5, 0.5, 0.5, 1);///灰色背景R,G,B,A 其中A為半透明Alpha值

    glClear(GL_COLOR_BUFFER_BIT |GL_DEPTH_BUFFER_BIT);

    glPushMatrix();///備分矩陣

        glTranslatef((x-150)/150.0, -(y-150)/150.0, z);

        glColor3f(1, 1, 0);

        glutSolidTeapot(0.3);

    glPopMatrix();///還原矩陣

    glutSwapBuffers();

}

void mouse(int button, int state, int mouseX, int mouseY)

{///設置錨點，避免瞬間移動的問題

    oldX = mouseX; oldY = mouseY;

}

void motion(int mouseX, int mouseY)

{

    x +=(mouseX-oldX);

    y +=(mouseY-oldY);

    oldX = mouseX;

    oldY = mouseY;

    display();

}

void keyboard( unsigned char key, int mouseX, int mouseY )

{

}

int main(int argc, char** argv)

{

    glutInit( &argc, argv);

    glutInitDisplayMode( GLUT_DOUBLE | GLUT_DEPTH );

    glutCreateWindow("week05 keyboard");

    glutDisplayFunc(display);

    glutKeyboardFunc(keyboard);///鍵盤事件函式

    glutMouseFunc(mouse);

    glutMotionFunc(motion);

    glutMainLoop();

}

```

縮放函式glScalef()

3.加上縮放函式，在motion函式中改寫公式

```

#include <stdio.h>///印出用

#include <GL/glut.h>

float x=150, y=150, z=0, scale=1.0;///座標設定為150, 150在視窗正中央

int oldX=0, oldY=0;

void display()

{

    glClearColor(0.5, 0.5, 0.5, 1);///灰色背景R,G,B,A 其中A為半透明Alpha值

    glClear(GL_COLOR_BUFFER_BIT |GL_DEPTH_BUFFER_BIT);

    glPushMatrix();///備分矩陣

        glTranslatef((x-150)/150.0, -(y-150)/150.0, z);

        glScalef(scale, scale, scale);///x,y,z縮放為 scale倍，維持原有比例

        glColor3f(1, 1, 0);

        glutSolidTeapot(0.3);

    glPopMatrix();///還原矩陣

    glutSwapBuffers();

}

void mouse(int button, int state, int mouseX, int mouseY)

{///重設圖案位置，避免瞬間移動的問題

    oldX = mouseX; oldY = mouseY;

}

void motion(int mouseX, int mouseY)

{

    if(mouseX-oldX >0) scale *=1.01;

    if(mouseX-oldX <0) scale -=0.99;///+-百分之一

    

    oldX = mouseX;

    oldY = mouseY;

    display();

}

void keyboard( unsigned char key, int mouseX, int mouseY )

{

}

int main(int argc, char** argv)

{

    glutInit( &argc, argv);

    glutInitDisplayMode( GLUT_DOUBLE | GLUT_DEPTH );

    glutCreateWindow("week05 keyboard");

    glutDisplayFunc(display);

    glutKeyboardFunc(keyboard);///鍵盤事件函式

    glutMouseFunc(mouse);

    glutMotionFunc(motion);

    glutMainLoop();

}

```

未完待續...